compress_filter.c

   1 /*
   2  * Copyright (C) 2005-2009 Andre Noll <maan@systemlinux.org>
   3  *
   4  * Licensed under the GPL v2. For licencing details see COPYING.
   5  */
   6
   7 /** \file compress_filter.c Paraslash's dynamic audio range compressor. */
   8
   9 /*
  10  * Uses ideas of AudioCompress, (C) 2002-2004  M. Hari Nezumi <magenta@trikuare.cx>
  11  */
  12
  13 #include "para.h"
  14 #include "compress_filter.cmdline.h"
  15 #include "list.h"
  16 #include "sched.h"
  17 #include "ggo.h"
  18 #include "filter.h"
  19 #include "string.h"
  20 #include "error.h"
  21
  22 /** The size of the output data buffer. */
  23 #define COMPRESS_CHUNK_SIZE 40960
  24
  25 /** Data specific to the compress filter. */
  26 struct private_compress_data {
  27         /** The current multiplier. */
  28         unsigned current_gain;
  29         /** Points to the configuration data for this instance of the compress filter. */
  30         struct compress_filter_args_info *conf;
  31         /** Maximal admissible gain. */
  32         unsigned max_gain;
  33         /** Number of samples already seen. */
  34         unsigned num_samples;
  35         /** Absolute value of the maximal sample in the current block. */
  36         int peak;
  37 };
  38
  39 static ssize_t compress(char *inbuf, size_t inbuf_len, struct filter_node *fn)
  40 {
  41         size_t i, length = PARA_MIN((inbuf_len / 2) * 2,
  42                 (fn->bufsize - fn->loaded) / 2 * 2);
  43         struct private_compress_data *pcd = fn->private_data;
  44         int16_t *ip = (int16_t *)inbuf, *op = (int16_t *)(fn->buf + fn->loaded);
  45         unsigned gain_shift = pcd->conf->inertia_arg + pcd->conf->damp_arg,
  46                 mask = (1 << pcd->conf->blocksize_arg) - 1;
  47
  48         if (!length)
  49                 return 0;
  50         for (i = 0; i < length / 2; i++) {
  51                 /* be careful in that heat, my dear */
  52                 int sample = *ip++, adjusted_sample = (PARA_ABS(sample) *
  53                         pcd->current_gain) >> gain_shift;
  54                 if (unlikely(adjusted_sample > 32767)) { /* clip */
  55                         PARA_NOTICE_LOG("clip: sample: %d, adjusted sample: %d\n",
  56                                 sample, adjusted_sample);
  57                         adjusted_sample = 32767;
  58                         pcd->current_gain = (3 * pcd->current_gain +
  59                                 (1 << pcd->conf->inertia_arg)) / 4;
  60                         pcd->peak = 0;
  61                 } else
  62                         pcd->peak = PARA_MAX(pcd->peak, adjusted_sample);
  63                 *op++ = sample >= 0? adjusted_sample : -adjusted_sample;
  64                 if (likely(++pcd->num_samples & mask))
  65                         continue;
  66 //              PARA_DEBUG_LOG("gain: %u, peak: %u\n", pcd->current_gain,
  67 //                      pcd->peak);
  68                 if (pcd->peak < pcd->conf->target_level_arg) {
  69                         if (pcd->current_gain < pcd->max_gain)
  70                                 pcd->current_gain++;
  71                 } else
  72                         pcd->current_gain = PARA_MAX(pcd->current_gain - 2,
  73                                 1U << pcd->conf->inertia_arg);
  74                 pcd->peak = 0;
  75         }
  76         fn->loaded += length;
  77         return length;
  78 }
  79
  80 static void close_compress(struct filter_node *fn)
  81 {
  82         free(fn->private_data);
  83         free(fn->buf);
  84 }
  85
  86 /** TODO: Add sanity checks */
  87 static int compress_parse_config(int argc, char **argv, void **config)
  88 {
  89         int ret;
  90         struct compress_filter_args_info *compress_conf
  91                 = para_calloc(sizeof(*compress_conf));
  92
  93         ret = -E_COMPRESS_SYNTAX;
  94         if (compress_cmdline_parser(argc, argv, compress_conf))
  95                 goto err;
  96         *config = compress_conf;
  97         return 1;
  98 err:
  99         free(compress_conf);
 100         return  ret;
 101 }
 102
 103 static void open_compress(struct filter_node *fn)
 104 {
 105         struct private_compress_data *pcd = para_calloc(
 106                 sizeof(struct private_compress_data));
 107         pcd->conf = fn->conf;
 108         fn->private_data = pcd;
 109         fn->bufsize = COMPRESS_CHUNK_SIZE;
 110         fn->buf = para_malloc(fn->bufsize);
 111         pcd->current_gain = 1 << pcd->conf->inertia_arg;
 112         pcd->max_gain = 1 << (pcd->conf->inertia_arg + pcd->conf->aggressiveness_arg);
 113 }
 114
 115 /**
 116  * The init function of the compress filter.
 117  *
 118  * \param f Pointer to the struct to initialize.
 119  */
 120 void compress_filter_init(struct filter *f)
 121 {
 122         struct compress_filter_args_info dummy;
 123
 124         compress_cmdline_parser_init(&dummy);
 125         f->open = open_compress;
 126         f->close = close_compress;
 127         f->convert = compress;
 128         f->parse_config = compress_parse_config;
 129         f->help = (struct ggo_help) {
 130                 .short_help = compress_filter_args_info_help,
 131                 .detailed_help = compress_filter_args_info_detailed_help
 132         };
 133 }